Alright, let's work through 1638 times 7522 step by step
1638 × 7522 = 7522 × (1638)
+ 7522 × 8 which equals 60176
+ 7522 × 30 producing 225660
+ 7522 × 600 which equals 4513200
+ 7522 × 1000 producing 7522000

= 12321036
